Cellular and humoral factors governing canine mixed lymphocyte cultures after renal transplantation: III. Further studies with antibody

Further studies have been performed on the unidirectional mixed lymphocyte culture (MLC) in dogs after renal transplantation. A high sensitivity of this assay as a test for antibody was demonstrated. Specific inhibitory activity against donor cells was found in recipient sera beginning 5 days after transplantation and was also present in eluates obtained from rejecting kidneys removed at this time. No cytotoxic antibody was found in the serum or eluates at this time using the microcytotoxicity test. The duration of serum MLC inhibitory activity (in months) correlated with the time.in days (2-14) that the allograft was allowed to remain in the recipient. Absorption with donor spleen cells removed MLC inhibitory activity. Finally, a discriminatory test for the presence of blocking antibody in contrast to cytotoxic antibody is described.